1. Field of the Invention
This invention relates to a process for producing an improved modified plant protein having thermoplastic and forming properties similar to casein and caseinate salts. The process involves the production of carbon dioxide by a yeast-sugar reaction, the conversion of it to a carbonate, and the reaction of the carbonate with the plant protein material to produce a reaction product. Peroxide is then added to the reaction product and the peroxide containing reaction product is then neutralized. The reaction product is then heated under a vacuum.
2. Description of the Prior Art
Casein, a milk protein, and its salts are used extensively in the food industry to manufacture fabricated food products. One of the major reasons for the polularity of casein and caseinate salts in fabricated foods is its unique functional properties such as high water solubility and the thermoplastic behavior of caseinate-water mixtures. By thermoplastic behavior, in this context, is meant the ability of a protein dough to flow freely like a liquid upon application of heat and a return to a semi-solid elastic mass upon cooling to ambient temperatures. Unmodified plant proteins generally lack this property and therefore cannot be used as a functional replacement of caseinate salts although the cost considerations favor their use. U.S. Pat. Nos. 3,917,877, 3,917,878, 3,917,879, and 3,930,058 have described processes used to modify plant proteins to simulate the thermoplastic properties of casein or caseinate salts. In all of the processes taught in the above patents, unmodified plant protein was treated with alkali. The alkali treatment of plant protein produces a product having a muddy green color and a strong odor characteristic of hydrogen sulfide. It has been observed that the color, odor and flavor of the alkali treated plant protein is highly objectionable and undesirable.
We have now developed a process by which the flavor and color of alkali-modified plant protein can be improved to yield a protein of highly desirable creamy white color and bland flavor. According to the developed process, the alkali-modified solution of plant protein or a mixture of alkali-modified plant protein and animal protein is reacted with a peroxide solution, followed by removal of steam volatile flavor components. The latter may be accomplished by heating the peroxide treated protein solution under a vacuum and removing the vapors. The relative amount of peroxide added and the time and temperature of peroxide treatment determine the extent of improvement in color, odor and flavor.